Portable electronic devices may become contaminated with bacteria or other infectious agents, and thus may be a medium for the transfer of infection from one user to another. Even when a device is used essentially only by a single user, if the device becomes contaminated, the user is exposed to the risk of infection for as long as the device remains contaminated.
Ultraviolet radiation in the 200-300 nanometer (nm) range is effective at killing microorganisms such as airborne and surface bacteria, viruses, yeasts, and molds. A germicidal effectiveness curve (based upon the effect of various wavelengths of radiation on a common bacterium) indicates a peak of photic absorption by the bacterial DNA at 254 nm. There are commercially available light sources that generate UV light in the wavelength range of about 200 nm to about 300 nm, which encompasses the effectiveness peak. Such light sources are used extensively in air and water purification applications in the food and beverage industry, in medical sterilization applications, drinking water purification, and sewage treatment.
While UV light is helpful in sterilizing surfaces, overexposure to short wave UV rays can be harmful to humans. Studies have shown ill effects of overexposure to UV rays found in solar energy. Similarly, overexposure to lamp-emitted germicidal UV radiation can cause erythema of the skin similar to sunburn, and direct exposure to the eyes can cause painful inflammation of the conjunctiva, cornea and iris, or even lasting damage. Persons working extensively with UV light generally are advised to wear special goggles or be shielded by non-UV transmitting protective plate glass. Children's skin and eyes are particularly sensitive to UV exposure. Therefore, measures need to be taken to reduce the risk of accidental or uninformed exposure to UV radiation.
In U.S. Pat. No. 6,953,940, the assignee of the present invention disclosed a device to sanitize dental equipment, such as toothbrushes, by exposing the equipment to ultraviolet radiation, commonly at a wavelength of about 254 nm.
However, there is a continuing need for a sanitizing device that is compact, safe, reliable, and efficient and which can be used for sanitizing handheld and portable electronic devices.